This invention relates to a process for the production of poly (urethane silicate) cellular solid or solid product by reacting a liquid isocyanate-terminated polyurethane prepolyer with a fine granular oxidated silicon compound. The prepolymer may be cured with a catalyst such as water. The poly (urethane silicate) products may be quite varied in physical properties; they may be solid or porous, rigid or elastomeric, and the porous products may be rigid or soft and flexible.
The poly (urethane silicate) cellular solid or solid products produced by this method may be utilized as thermal insulating material, noise insulating material, shock-resistant packing, cushions, as coating agents, as adhesives, as casting material. as constructional components of a building, etc. The products have improved heat and flame resistant properties.
In U.S. patent application Ser. No. 663,924, filed on Mar. 4, 1976 now U.S. Pat. No. 4,097,424 and U.S. patent application Ser. No. 599,000, now U.S. Pat. No. 4,072,637 silicon acids are reacted with polyisocyanate compounds, but not with liquid isocyanate-terminated polyrethane prepolymers. The reaction of oxidized silicon compound with polyurethanes and isocyanates were listed in U.S. patent application Ser. No. 71,628, filed Sept. 11, 1970 by David H. Bount now abandoned. The oxidized silicon compounds were called "oxidized silicate" and included alkali metal silicates, alkaline earth metal silicates, mono-alkali metal silicic acid, mono-alkaline earth silicic acid and silicic acid.
The oxidated silicon compounds may be produced by any of the commonly known methods. They are preferred to be in a fine granular form. The oxidated silicon compounds include hydrated silica, hydrated silica containing Si-H bonds (siliconformic acid), alkali metal silicates, alkaline earth metal silicates and natural occuring oxidated silicon compounds with free silicic acid radicals. The hydrated silica includes the various silicon acids such as dry silicic acid gel, orthosilicic acid, metasilicic and, monosilandiol, polysilicoformic acid, orthosilicoformic acid (Leucone), silicoformic acid and silica sol. Cement, such as Portland cement, contains oxidated silicon compounds and may be used in this invention.
The oxidated silicon compounds may be reacted with alkali metal compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and lithium hydroxide to produde alkali metal silicates and mono-alkali metal silicates which may be used in this invention.
As is known in the art, the isocyanate-terminated liquid polyurethane prepolymers may be made by reacting organic polyisocyanates in molar excess with hydroxyl containing or carboxyl containing polyesters, polyesters, polysulfides, polybutadienes, butadiene-acrylonitrile copolymer and butadiene-styrene copolymer, polyepichlorohydrin, polythioethers, polyester amides, polyacetals, urea formaldehyde resins, polycarbonates, organic hydroxyl silicate compounds, organic polyester silicates, and other polyols. The polyesters may be produced by any of the commonly known methods. The polyether polyols are useful in making polyurethane prepolymers, and the methods to produce them as well known in the art. The hydroxyl-group containing polysulfide polymers may be utilized to produce polyurethane prepolymers.
Any suitable polyisocyanate may be reacted with the above described hydroxyl containing polymers to prepare the isocyanate-terminated methane prepolymers such as the arylene polyisocyanates, alkylene polyisocyanates and triphenylmethane triisocyanate. Toluene diisocyanates are preferred, especially a mixture of the 2,4-isomer and 2,6-isomer. Phosgenation product of aniline-formaldehyde condensation may be used.
Plasticizers, fillers, curing rate modifiers, pigments, extenders and the like may be added to the polyurethane prepolymer or may be added at the time of curing and may be in the amount from 5% to 50% by weight, based on the prepolymer. Plasticizers may include benzoate ester, phthalate esters, dipropylene glycol benzoate, dodecyl phthalate and propylene glycol phthalate. Extenders such as high boiling cold tar distillates, mineral oil, poly (alpha-methyl styrene) polymers, mercapto-terminated liquid polysulfide polymers, paraffin oil and sulphonated caster oil may be used. Finely divided fillers such as alkali metal silicate, alkaline earth metal silicates, ammonium silicate, metal oxides, metal hydroxides, metal carbonates, chalk, heavy spar, gypsum anhydrite, clay, kaolin, silica and mixtures thereof may be used in this invention.
In the production of certain foams, it is advisable to add blowing agents. These are inert liquids with boiling points ranging from -25.degree. to 80.degree. C. and preferably from -15.degree. to 40.degree. C. The organic blowing agents are used in quantities of from 0% to 30% by weight, based on the reaction mixture.
The organic blowing agents such as acetone, ethyl acetate, methanol, ethanol, halogenated alkanes, e.g. methylene chloride, chloroform, ethylidene chloride, vinylidene chloride, monofluorotrichloromethane, chlorodiflouromethane, dichlorodiflouromethane, butane, hexane, diethylether, compounds which decompose at temperatures above room temperature with liberation of gases, e.g. nitrogen, such as azo compounds and azoisobutyric acid nitrile may be used in this process.
Other curing catalysts in place of or combined with water may be utilized as the catalyst to produce foam products from the liquid isocyanate-terminated polymethane prepolymers and oxidized silicon compounds. These catalysts are commonly known in the arts such as tertiary amines, silaamine, basic compounds which contain nitrogen, e.g. tetraalkylammonium hydroxide, alkali metal hydroxides, alkali metal phenolates, alkali metal alcoholates, hexahydrotriazines, tin organo-metallic and mixtures thereof. Acetic acid may be used as the catalyst. These catalysts are generally used in a quantity of from 0.001% to 50% by weight, based on the weight of the polyurethane prepolymer.
Suitable emulsifiers and foam stabilizers may also be used according to this invention. Suitable emulsifiers are, e.g. the sodium salts of ricinoleic sulphonates or of fatty acids, or salts of fatty acids with amines, e.g. oleic acid diethylamine or stearic acid diethanolamine, or alkali metal or ammonium salts of sulphonic acids and fatty acids. These additives are preferably used in quantities of from 0% to 20% by weight, based on the reaction mixtures.
Suitable foam stabilizers are mainly water soluble polyether siloxanes and those described, in U.S. Pat. No. 3,629,308. These additives are preferably used in quantities of from 0% to 20%, by weight, based on the reaction mixture.
Further examples of surface active additives, foam stabilizers, cell regulators, negative catalysts, stabilizers, flame retarding substances, plasticizers, dyes, fillers and fungicidal and bacteriocidal substances and details about methods of using these additives and their actions may be found in Kunststoff-Handbuch, Volume VI, published by Vieweg and Hochtlen, Carl-Hanser-Verlag, Munich 1966, e.g. on pages 103 to 113.
The polyurethane prepolymer with only two terminal isocyanate groups tend to produce non-porous products when reacted with an oxidated silicon compound and then cured by a catalyst. The polyurethane prepolymer with 3 or more terminal isocyanate groups tend to produce cellular products when reacted with an oxidated silicon compound and then cured with a curing catalyst. Mixtures of polyurethane prepolymer with 3 and 4 terminal isocyanate groups, when reacted with an oxidated silicon compound and then cured, produce a tough, strong, fine cellular, lightweight poly (urethane silicate) product which is useful for structural applications. The three and four terminal isocyanate groups may be mixed to contain from 20% to 80% by weight of the prepolymer having three isocyanate groups, and from 80% to 20% by weight of the prepolymer having four isocyanate groups.
Any suitable polyisocyanate may be used to produce the liquid isocyanate-terminated polyurethane prepolymers, for example, arylene polyisocyanates such as tolylene, metaphenylene; 4-chlorophenylene-1,3, methylene-bis-(phenylene-4-), biphenylene-4,4'-, 3,3'-dimethoxy-biphenylene-4,4'-, 3,3'-diphenylbiphenylene-4,4'-, naphthalene-1,5-, and tetrahydro-napthalene-1,5-diisocyanates and triphenylmethane triisocyanate, alkylene polyisocyanates such as ethylene, ethylidene, propylene-1,2-, butylene-1, 4-butylene-1,3-, hexylene-1,6-, decamethylene-1,10-, cyclohexylene-1,2-, cyclohexylene-1,4-, and methylene-bis-(cyclohexyl- 4,4'-) diisocyanates. Phosgenation products of aniline-formaldehyde condensation may be used. Polyisothiocyanates, inorganic polyisothiocyanates, polyisocyanates which contain carbodiimide groups as described in German Pat. No. 1,092,007 and polyisocyanates which contain urethane groups, allophanate groups, isocyanurate groups, urea groups, imide groups or biuret groups may be used to produce the liquid isocyanate-terminated polyurethane prepolymers.
The preferred method to produce poly(urethane silicate) solid/cellular solid product is to mix 2 to 6 parts by weight of a liquid isocyanate-terminated polyurethane prepolymer with 1 to 2 parts by weight of a fine granular oxidated silicon compound. The mixture is then heated to 20.degree. C. to 80.degree. C., preferably 40.degree. C. to 80.degree. C. while agitating for 10 to 30 minutes thereby producing a poly(urethane silicate) prepolymer. A curing catalyst, such as water, is added in the amount of 0 to 1 part by weight to the prepolymer and is mixed thoroughly then gently agitated for 3 to 15 minutes until the mixture solidifies or begins to expand. It will expand 3 to 12 times its original volume to produce a poly(urethane silicate)solid/cellular solid product.
An alkali metal carbonate or hydroxide in the amount of 1% to 10% by weight, percentage based on weight of the oxidized silicon compound, may be added with the oxidated silicon compound to enhance the chemical reaction between the polyurethane prepolymer and the oxidated silicon compound. Alkali metal silicates may be used in place of the oxidation silicon compounds.
Plasticizers, fillers, curing rate modifiers, pigments, extenders, flame retarding substances, blowing agents, fungicidal and bacteriocidal agents, foam stabilizers, etc. may be added to the poly(urethane silicate) prepolymer in the amount 5% to 50% by weight, based on the prepolymer.
Surface active additives, emulsifiers, and foam stabilizers may be added to the curing catalyst. In some cases the foaming is started by heating the poly(urethane silicate) prepolymer to 80.degree. to 100.degree. C.
In the production of certain poly(urethane silicate) solid or cellular solid product it is necessary to have a longer curing time, and in certain cases, it is necessary to heat the product at 80.degree. C. to 120.degree. C. for 1 to 3 hours to finish curing the product.
The object of the present invention is to provide a novel process to produce poly(urethane silicate) solid/cellular solid products from reacting liquid isocyanate-terminated polyurethane prepolymers and oxidated silicon compounds. Another object and advantage of the present invention is to utilize low cost and ready availability of oxidated silicon compound to react with the liquid isocyanate-terminated polyurethane prepolymers. An other object is to produce relatively low cost, rigid, elastomeric and cellular solid poly(urethane silicate) products having good physical properties. Another object of the present invention is to produce poly(urethane silicte) solid/cellular solid products with improved flame resistant properties. Still a further object is to provide a novel, relatively low cost, rigid, fine cellular, light-weight poly(urethane silicate) product which may be used for structural purposes. Still another object is to produce novel poly(urethane silicate) solid/cellular solid products that are soluble in organic solvents and may be utilized as a coating agent for wood and metal .